The purpose of this study is to examine data at three points in time to investigate: (1) the personality, family (mostly parental), and peer etiological correlates of movement in youngster's stage of drug use and (2) the effect of marijuana use on subsequent youngster personality and relationship variables. The sample consists of youngsters and their mothers who were interviewed first (T1) when the children were ages 3-10 (mothers only), and again at T2 when the children were 11-18 (mothers and children). The third (T3) data collection is part of this proposal and would involve mother and youngster interviews when the youngsters are 13-20. Separate interviews with mother and child will be conducted in their own home by trained interviewers. Scales with adequate psychometric properties measuring the independent variables will be developed from the interview schedules. The primary analytic technique will be either hierarchical multiple regression or causal analysis. The first overall aim is to explore how sets of early childhood and early and later adolescent attributes interrelate in their impact on the youngster's involvement (or noninvolvement) in stage of drug use over time. Also of concern is the exploration of the interaction of individual variables to see if certain drug-prone "risk" characteristics can be offset by non-drug prone "protective" characteristics. Both types of exploration should provide important knowledge for prevention and treatment efforts as they will help pinpoint those youngsters at risk for increased involvement in drug use and the areas in which they are most vulnerable and in need of help. As for the second major aim (examining the consequences of marijuana use), not only will subsequent changes in personality and behavior be examined but also changes in the youngster's family and peer relationships. At the present time, there are few longitudinal studies which examine changes such as these. Since this proposed study does have a longitudinal design, it can help provide much needed information on causality, a crucial element in determining drug attitudes and policy.